Extremely high prevalence of neural tube defects in a 4-county area in Shanxi Province, China

BACKGROUND: In the past, northern China's Shanxi Province has reported the highest incidence of neural tube defects (NTDs) in the world. However, little is known about the epidemiology of NTDs in this area in recent years. METHODS: Data were collected from a population-based birth defects surveillance system in 4 counties that captures information on all live births, stillbirths of at least 20 weeks' gestation, and pregnancy terminations at any gestational age resulting from prenatal diagnosis of a birth defect. We also surveyed mothers of NTD case patients to determine their use of folic acid before and during early pregnancy. RESULTS: During 2003, 160 NTD cases were identified among 11,534 births (NTD birth prevalence = 138.7/10,000 births). The rates of anencephaly, spina bifida and encephalocele were 65.9, 58.1, and 14.7 per 10,000, respectively, and a female predominance was observed among anencephaly cases (male-to-female relative risk [RR], 0.49; 95% confidence interval [CI], 0.30-0.79), but not among spina bifida (RR, 0.90; 95% CI, 0.55-1.45) and encephalocele (RR, 1.03; 95% CI, 0.40-2.69) cases. The percentages of pregnancy termination following prenatal diagnosis of anencephaly, spina bifida, and encephalocele were 50%, 41.8%, and 35.3%, respectively. NTD birth prevalence tended to be higher among mothers aged <20 or > or =30 years (P = .06) and was markedly associated with lower levels of maternal education (P < .001). Among 143 NTD mothers, only 6 (4.2%) used folic acid supplements during the periconceptional period. CONCLUSIONS: The NTD birth prevalence rate in the study area is among the highest worldwide. Folic acid deficiency may be one important risk factor.     

Uncoupling protein 2 polymorphisms as risk factors for NTDs

BACKGROUND: Both environmental and genetic factors are involved in the etiology of NTDs. Inadequate folate intake and obesity are important environmental risk factors. Several folate‐related genetic variants have been identified as risk factors; however, little is known about how genetic variants relate to the increased risk seen in obese women. Uncoupling Protein 2 (UCP2) is an attractive candidate to screen for NTD risk because of its possible role in obesity as well as energy metabolism, type‐2 diabetes, and the regulation of reactive oxygen species. Interestingly, a previous study found that a common UCP2 compound homozygous genotype was associated with a threefold increase in NTD risk. METHODS: We evaluated three polymorphisms, ‐866G>A, A55V, and the 3′UTR 45 bp insertion/deletion, as risk factors for NTDs in Irish NTD cases (n = 169), their mothers (n = 163), their fathers (n = 167), and normal control subjects (n = 332). RESULTS: Allele and genotype frequencies were not significantly different when comparing NTD mothers, NTD fathers, or affected children to controls. Additionally, the previously reported risk genotype (combined homozygosity of 55VV and 3′UTR 45 bp deletion/deletion) was not present at a higher frequency in any NTD group when compared to controls. CONCLUSIONS: In our Irish study population, UCP2 polymorphisms did not influence NTD risk. Moreover, the prevalence of this allele in other populations was similar to the Irish prevalence but far lower than reported in the previous NTD study, suggesting that this previous finding of an association with NTDs might have been due to an unrepresentative study sample. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.     

NTD prevalences in central California before and after folic acid fortification

BACKGROUND: In many regions, NTD prevalences were already declining prior to folic acid fortification. This study examined whether the declining prefortification (1989–1996) NTD prevalences continued into the postfortification period (1998–2003) in selected California counties. METHODS: This population‐based study used vital statistics data and birth defects registry data that were actively ascertained from medical records. The study population included all live births and stillbirths delivered in central California counties from 1989 to 2003. Cases included deliveries with NTDs during the same time period. RESULTS: For all NTDs combined, the slopes indicated that NTD prevalence was decreasing by 7.5 (slope: ?7.5; 95% CI: ?12.4, ?2.5) cases per 100,000 deliveries per year before fortification, whereas NTD prevalence was no longer decreasing after fortification. Comparison of the difference in the two slopes indicated that the postfortification slope exceeded the prefortification slope by 12.6 (95% CI: 2.6, 22.6) cases per 100,000 deliveries per year. CONCLUSIONS: Annual NTD prevalences in central California did not continue to decrease after implementation of folic acid fortification. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.     

Prevention of NTDs with periconceptional multivitamin supplementation containing folic acid in China

BACKGROUND: Maternal nutritional factors seem to contribute substantially to the complex etiologies of NTDs. Foremost among these factors is the periconceptional use of supplementation containing folic acid, which is associated with a reduction in the risk of women having NTD‐affected pregnancies. This study was designed to observe the effectiveness of multivitamin supplementation containing folic acid in preventing NTDs in a Chinese population and to detect factors that would impact the effectiveness. METHODS: Through family planning networks, a population‐based community intervention study was carried out in 18 counties of China. Participants were divided into an intervention (taking multivitamin) group and a control group, and were followed up according to periconceptional multivitamin supplementation (in general 6 mg) for 2 years. Women who had a pregnancy were followed up from 28 weeks gestation at least to pregnancy termination, and the outcome was recorded. The incidence rate of the two groups and the relative risks were calculated to evaluate the efficacy of the multivitamin supplement in preventing NTDs. RESULTS: During 2000 and 2002, all of the women having pregnancies with birth defects and women whose pregnancies were without any birth defects were interviewed. Nine NTDs were recorded from 25,444 pregnancies (NTD birth prevalence = 0.35/1,000 pregnancies) in the intervention group and 48 NTDs among 26,599 pregnancies (NTD birth prevalence = 1.80/1,000 pregnancies) in the control group. The protective rate was 80.4%. CONCLUSIONS: Periconceptional multivitamin supplementation containing folic acid can prevent the occurrence of NTDs with the beneficial effect dependent on the frequency and timing of the supplementation. Our study suggests that multivitamin supplement containing folic acid taken from a time point of 2 months before conception and continuing until completion of the second month after conception and taken more than five times per week can significantly reduce the risks of NTDs. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.     

High prevalence of NTDs in Shanxi Province: a combined epidemiological approach

BACKGROUND: Shanxi Province has historically reported a high prevalence of NTDs. In order to establish baseline rates for NTDs and discuss the risk factors associated with sociodemographic, maternal characteristics, and geographic factors, we performed the present study using an approach combining population and hospital-based methodologies. METHODS: We used chi(2) and Fisher's exact tests to evaluate variation in the prevalence by selected covariates and computed crude ORs and 95% CIs. Adjusted odds ratios (AORs) were performed using logistic regression with all the covariates included in the model. RESULTS: The overall NTD prevalence during the 3 year study period was 199.38 per 10,000 births, with a higher NTD prevalence clustered in 46 villages within this geographic area. However, no statistical significance was found between NTD prevalence and the elevation of the villages or their distance from coal plants. AORs revealed women aged 20 and above had a lower risk of NTDs compared to those younger than 20 (AOR range 0.4-0.5). A higher risk of NTDs was observed among female infants (AOR 1.50; 95% CI: 1.04-2.17), women with four or more previous births (AOR 2.80; 95% CI: 1.20-6.52), and a previous history of birth defects (AOR 3.23; 95% CI: 1.46-7.12). CONCLUSIONS: This study has documented a high prevalence of NTDs in Shanxi. Similar variations to other reports were found in the risk of NTDs by maternal demographic characteristics and a clustering of NTDs in certain villages that require further exploration.     

Describing the Prevalence of Neural Tube Defects Worldwide: A Systematic Literature Review

BackgroundFolate-sensitive neural tube defects (NTDs) are an important, preventable cause of morbidity and mortality worldwide. There is a need to describe the current global burden of NTDs and identify gaps in available NTD data.ConclusionsMany WHO member states (120/194) did not have any data on NTD prevalence. Where data are collected, prevalence estimates vary widely. These findings highlight the need for greater NTD surveillance efforts, especially in lower-income countries. NTDs are an important public health problem that can be prevented with folic acid supplementation and fortification of staple foods.     

Using Co-authorship Networks to Map and Analyse Global Neglected Tropical Disease Research with an Affiliation to Germany

Background

Research on Neglected Tropical Diseases (NTDs) has increased in recent decades, and significant need-gaps in diagnostic and treatment tools remain. Analysing bibliometric data from published research is a powerful method for revealing research efforts, partnerships and expertise. We aim to identify and map NTD research networks in Germany and their partners abroad to enable an informed and transparent evaluation of German contributions to NTD research.

Methodology/Principal Findings

A SCOPUS database search for articles with German author affiliations that were published between 2002 and 2012 was conducted for kinetoplastid and helminth diseases. Open-access tools were used for data cleaning and scientometrics (OpenRefine), geocoding (OpenStreetMaps) and to create (Table2Net), visualise and analyse co-authorship networks (Gephi). From 26,833 publications from around the world that addressed 11 diseases, we identified 1,187 (4.4%) with at least one German author affiliation, and we processed 972 publications for the five most published-about diseases. Of those, we extracted 4,007 individual authors and 863 research institutions to construct co-author networks. The majority of co-authors outside Germany were from high-income countries and Brazil. Collaborations with partners on the African continent remain scattered. NTD research within Germany was distributed among 220 research institutions. We identified strong performers on an individual level by using classic parameters (number of publications, h-index) and social network analysis parameters (betweenness centrality). The research network characteristics varied strongly between diseases.

Conclusions/Significance

The share of NTD publications with German affiliations is approximately half of its share in other fields of medical research. This finding underlines the need to identify barriers and expand Germany’s otherwise strong research activities towards NTDs. A geospatial analysis of research collaborations with partners abroad can support decisions to strengthen research capacity, particularly in low- and middle-income countries, which were less involved in collaborations than high-income countries. Identifying knowledge hubs within individual researcher networks complements traditional scientometric indicators that are used to identify opportunities for collaboration. Using free tools to analyse research processes and output could facilitate data-driven health policies. Our findings contribute to the prioritisation of efforts in German NTD research at a time of impending local and global policy decisions.     

Decline in the prevalence of neural tube defects following folic acid fortification and its cost-benefit in South Africa

BACKGROUND: In October 2003 South Africa embarked on a program of folic acid fortification of staple foods. We measured the change in prevalence of NTDs before and after fortification and assessed the cost benefit of this primary health care intervention. METHODS: Since the beginning of 2002 an ecological study was conducted among 12 public hospitals in four provinces of South Africa. NTDs as well as other birth defect rates were reported before and after fortification. Mortality data were also collected from two independent sources. RESULTS: This study shows a significant decline in the prevalence of NTDs following folic acid fortification in South Africa. A decline of 30.5% was observed, from 1.41 to 0.98 per 1,000 births (RR = 0.69; 95% CI: 0.49–0.98; p = .0379). The cost benefit ratio in averting NTDs was 46 to 1. Spina bifida showed a significant decline of 41.6% compared to 10.9% for anencephaly. Additionally, oro‐facial clefts showed no significant decline (5.7%). An independent perinatal mortality surveillance system also shows a significant decline (65.9%) in NTD perinatal deaths, and in NTD infant mortality (38.8%). CONCLUSIONS: The decrease in NTD rates postfortification is consistent with decreases observed in other countries that have fortified their food supplies. This is the first time this has been observed in a predominantly African population. The economic benefit flowing from the prevention of NTDs greatly exceeds the costs of implementing folic acid fortification. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.     

Folate, homocysteine and neural tube defects: an overview

Folate administration substantially reduces the risk on neural tube detects (NTD). The interest for studying a disturbed homocysteine (Hcy) metabolism in relation to NTD was raised by the observation of elevated blood Hcy levels in mothers of a NTD child. This observation resulted in the examination of enzymes involved in the folate-dependent Hcy metabolism. Thus far, this has led to the identification of the first and likely a second genetic risk factor for NTD. The C677T and A1298C mutations in the methylenetetrahydrofolate reductase (MTHFR) gene are associated with an increased risk of NTD and cause elevated Hcy concentrations. These levels can be normalized by additional folate intake. Thus, a dysfunctional MTHFR partly explains the observed elevated Hcy levels in women with NTD pregnancies and also, in part, the protective effect of folate on NTD. Although the MTHFR polymorphisms are only moderate risk factors, population-wide they may account for an important part of the observed NTD prevalence.     

A polymorphism,R653Q,in the trifunctional enzyme methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase is a maternal genetic risk factor for neural tube defects: report of the Birth Defects Research Group

Women who take folic acid periconceptionally reduce their risk of having a child with a neural tube defect (NTD) by >50%. A variant form of methylenetetrahydrofolate reductase (MTHFR) (677C-->T) is a known risk factor for NTDs, but the prevalence of the risk genotype explains only a small portion of the protective effect of folic acid. This has prompted the search for additional NTD-associated variants in folate-metabolism enzymes. We have analyzed five potential single-nucleotide polymorphisms (SNPs) in the cytoplasmic, nicotinamide adenine dinucleotide phosphate-dependent, trifunctional enzyme methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase (MTHFD1) for an association with NTDs in the Irish population. One SNP, R653Q, in this gene appears to be associated with NTD risk. We observed an excess of the MTHFD1 "Q" allele in the mothers of children with NTD, compared with control individuals. This excess was driven by the overrepresentation of QQ homozygotes in the mothers of children with NTD compared with control individuals (odds ratio 1.52 [95% confidence interval 1.16-1.99], P=.003). We conclude that genetic variation in the MTHFD1 gene is associated with an increase in the genetically determined risk that a woman will bear a child with NTD and that the gene may be associated with decreased embryo survival.     

Does prenatal screening for 5,10-methylenetetrahydrofolate reductase (MTHFR) mutations in high-risk neural tube defect pregnancies make sense?

Despite the fact that neural tube defects (NTDs) are the most common congenital malformations of the central nervous system, investigators have yet to identify responsible gene(s). Research efforts have been productive in the identification of environmental factors, such as periconceptional folic acid supplementation, that modulate risk for the development of NTDs. Studies of the folic acid biosynthetic pathway led to the discovery of an association between elevated levels of homocysteine and NTD risk. Researchers subsequently identified single nucleotide polymorphisms in the gene coding for the enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR). Association studies suggested it was a potential risk factor for NTDs, because the thermolabile form of the enzyme led to elevated homocysteine concentrations when folic acid intake is low. Numerous studies analyzing MTHFR variants have resulted in positive associations with increased NTD risk only in certain populations, suggesting that these variants are not large contributors to the etiology of NTDs. With our limited understanding of the genes involved in regulating NTD susceptibility, the paucity of data on how folic acid protects the developing embryo, as well as the observed decrease in birth prevalence of NTDs following folic acid supplementation and food fortification, it makes little sense for prospective parents to be tested for MTHFR variants, or for variants of other known folate pathway genes.     

Towards a shared understanding of sustainability for neglected tropical disease programs

BackgroundSustainability within neglected tropical disease (NTD) programs is a complex and challenging issue. The need for a shared understanding about what sustainability means for NTD programs is more important than ever as stakeholders are currently realigning for the next decade of NTD programming with the launch of WHO’s new NTD roadmap for 2012–2030. The aim of this paper is to assess different perspectives to generate a working definition of sustainability for NTD programs.Methodology/Principal findingsThis study surveyed affiliates of the NTD NGO Network (NNN) about their definitions of sustainability and then analyzed the data using an inductive and deductive process. The research team drafted a sustainability statement based on the survey findings and then solicited and incorporated feedback on the statement from a diverse group of expert reviewers. The final statement includes a working definition of sustainability for NTD programs that highlights three key essential components to sustainability: domestic commitment, responsive resource mobilization, and accountability.Conclusions/SignificanceThis research resulted in a sustainability statement, based on a survey and extensive consultation with stakeholders, that represents a starting point for shared understanding around the concept of sustainability for NTD programs. Future collaborative work should build off this definition and seek to incorporate indicators for sustainability into programmatic decision-making.     

Impact of folic acid food fortification on the birth prevalence of lipomyelomeningocele in Canada

BACKGROUND: Recent studies reported no reduction in the frequency of lipomeningomyelocele (LMMC) in Hawaii and Nova Scotia after the implementation of a folic acid food fortification policy in 1998, while a marked reduction in the prevalence of other NTDs was observed. This study was performed to assess the prevalence of LMMC in Canada in relation to the timing of food fortification. METHODS: The study population included livebirths, stillbirths, and terminations of pregnancies because of fetal anomaly to women residing in seven Canadian provinces, from 1993 to 2002. In each province, the ascertainment of NTD cases relied on multiple sources, and in addition all medical charts were reviewed. The study period was divided into pre‐, partial, and full fortification periods, based on results of red cell folate tests published in the literature. RESULTS: A total of 86 LMMC cases were recorded among approximately 1.9 million live births. The average birth prevalence rate was 0.05/1,000, ranging from a minimum of 0.01/1,000 in 2002 to a maximum of 0.08/1,000 in 1999. There was statistical heterogeneity between years (p = .01), but no pattern compatible with a decrease following fortification. Comparing the full fortification period with the prefortification period, there was a slight but not statistically significant decrease in LMMC birth prevalence. CONCLUSIONS: LMMC seems to be pathogenically distinct from myelomeningocele and more studies are needed to understand the embryologic mechanisms leading to this condition, and the environmental and genetic factors involved in its etiology. Birth Defects Research (Part A), 2008. © 2007 Wiley‐Liss, Inc.     

Folate-mediated one-carbon metabolism and neural tube defects: balancing genome synthesis and gene expression

Neural tube defects (NTDs) refer to a cluster of neurodevelopmental conditions associated with failure of neural tube closure during embryonic development. Worldwide prevalence of NTDs ranges from approximately 0.5 to 60 per 10,000 births, with regional and population-specific variation in prevalence. Numerous environmental and genetic influences contribute to NTD etiology; accumulating evidence from population-based studies has demonstrated that folate status is a significant determinant of NTD risk. Folate-mediated one-carbon metabolism (OCM) is essential for de novo nucleotide biosynthesis, methionine biosynthesis, and cellular methylation reactions. Periconceptional maternal supplementation with folic acid can prevent occurrence of NTDs in the general population by up to 70%; currently several countries fortify their food supply with folic acid for the prevention of NTDs. Despite the unambiguous impact of folate status on NTD risk, the mechanism by which folic acid protects against NTDs remains unknown. Identification of the mechanism by which folate status affects neural tube closure will assist in developing more efficacious and better targeted preventative measures. In this review, we summarize current research on the relationship between folate status and NTDs, with an emphasis on linking genetic variation, folate nutriture, and specific metabolic and/or genomic pathways that intersect to determine NTD outcomes.     

A screen for mutations in human homologues of mice exencephaly genes Tfap2alpha and Msx2 in patients with neural tube defects

BACKGROUND: Very little is known about the identity of genetic factors involved in the complex etiology of nonsyndromic neural tube defects (NTD). Potential susceptibility genes have emerged from the vast number of mutant mouse strains displaying NTD. Reasonable candidates are the human homologues of mice exencephaly genes Tfap2alpha and Msx2, which are expressed in the developing neural tube. METHODS: A single-strand conformation analysis (SSCA) mutation screen of the coding sequences of TFAP2alpha and MSX2 was performed for 204 nonsyndromic NTD patients including cases of anencephaly (n = 10), encephalocele (n = 8), and spina bifida aperta, SBA (n = 183). A selected number of SBA patients was additionally tested for specific mutations in MTHFD, FRalpha, and PAX1 already shown to be related to NTD. RESULTS: Two TFAP2alpha point mutations in individual SBA patients were silent on the amino acid level (C308C, T396T). On nucleic acid level, these mutations change evolutionary conserved codons and thus may influence mRNA processing and translation efficiency. One SBA patient displayed an exonic 9-bp deletion in MSX2 leading to a shortened and possibly less functional protein. None of these mutations was found in 222 controls. Seven polymorphisms detected in TFAP2alpha and MSX2 were equally distributed in patients and controls. Patients with combined heterozygosity of an exonic MSX2 and an intronic TFAP2alpha polymorphism were at a slightly increased risk of NTD (OR 1.71; 95% CI 0.57-5.39). CONCLUSIONS: Although several new genetic variants were found in TFAP2 and MSX2, no statistically significant association was found between NTD cases and the new alleles or their combinations. Further studies are necessary to finally decide if these gene variants may have acted as susceptibility factors in our individual cases.     

Genetic heterogeneity in neural tube defects.

In 1985-1987, the authors attempted to ascertain all cases of confirmed neural tube defects (NTD) in California and Illinois, not only among live-born infants (postnatal) but also cases ascertained during pregnancy (prenatal). Mothers of both prenatal and postnatal NTD cases were interviewed within 5 months. Among postnatal NTD cases, 14.9% (45/303) had anomalies not ordinarily associated with NTD. The frequency of non-NTD related anomalies was 9.4% (5/53) in anencephaly, 0/3 in craniorachischisis, 22.9% (8/35) in encephalocele, 14.5% (27/186) in spina bifida, 20% (1/5) in multiple NTD cases and 19% (4/21) in other NTDs. However, relatively few postnatal NTD cases had known multiple malformation patterns; Meckel-Gruber syndrome was the most common, with 2 postnatal cases, and 3 additional prenatal cases. Maternal age, paternal age and birth order in postnatal cases were 26.7 +/- 5.4 SD, 28.9 +/- 5.8 and 2.8 +/- 1.8, respectively. These characteristics were similar in prenatal NTD cases (27.9 +/- 6.0, 30.1 +/- 6.3, 2.5 +/- 1.5, respectively). We also found no differences in parental ages among different types of NTD. Frequency of prior spontaneous abortion differed neither between postnatal NTD (9.3%) and postnatal controls (8.1%), nor between prenatal NTD (10.7%) and prenatal control (8.7%). Loss rates in the pregnancy immediately prior to the index NTD cases were not significantly higher than in control subjects. The high frequency of non-NTD associated malformations (14.9%) indicates the caution must be exercised before assuming that a given NTD case is polygenic-multifactorial in etiology, especially cases of encephalocele.     

Heterogeneity of neural tube defects in Europe: the significance of site of defect and presence of other major anomalies in relation to geographic differences in prevalence.

In the period 1980-1987, neural tube defects were two to three times more prevalent in populations covered by EUROCAT registries in the United Kingdom and Ireland (UKI) than in Continental Europe and Malta (CEM). 1864 NTD cases in a total population of 580,000 births in UKI and 455 cases in a population of 380,000 births in CEM were analysed to find if there were differences in the ratio of prevalence rates between UKI and CEM according to site of the defect and association with non-central nervous system (CNS) anomalies. The prevalence rate ratio was high for anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida, and low for encephalocele, lower spina bifida, and anencephaly without other neural tube defects. There was a greater female excess for anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida than for other defects in both geographic areas. There was a female excess for encephalocele in UKI but a male excess in CEM. Certain sites (anencephaly with accompanying spina bifida, iniencephaly, and encephalocele) were more likely to have accompanying non-CNS anomalies. The prevalence rate ratio of multiply malformed NTD was in general lower than for isolated NTD but showed the same pattern by site. The prevalence rate ratio was high for multiply malformed anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida. The sex ratio was similar between isolated and multiply malformed cases when site of the defect is taken into account. It is concluded that the geographic prevalence pattern and sex ratio differ according to site of NTD but do not differ substantially according to whether NTD is isolated or associated with non-CNS anomalies.     

Low Birth Weight at Term and Its Determinants in a Tertiary Hospital of Nepal: A Case-Control Study

Birth weight of a child is an important indicator of its vulnerability for childhood illness and chances of survival. A large number of infant deaths can be averted by appropriate management of low birth weight babies and prevention of factors associated with low birth weight. The prevalence of low birth weight babies in Nepal is estimated to be about 12-32%.Our study aimed at identifying major determinants of low birth weight among term babies in Nepal. A hospital-based retrospective case control study was conducted in maternity ward of Tribhuvan University Teaching Hospital from February to July 2011. A total of 155 LBW babies and 310 controls were included in the study. Mothers admitted to maternity ward during the study period were interviewed, medical records were assessed and anthropometric measurements were done. Risk factors, broadly classified into proximal and distal factors, were assessed for any association with birth of low-birth weight babies. Regression analysis revealed that a history of premature delivery (adjusted odds ratio; aOR5.24, CI 1.05-26.28), hard physical work during pregnancy (aOR1.48, CI 0.97-2.26), younger age of mother (aOR1.98, CI 1.15-3.41), mothers with haemoglobin level less than 11gm/dl (aOR0.51, CI0.24-1.07) and lack of consumption of nutritious food during pregnancy (aOR1.99, CI 1.28-3.10) were significantly associated with the birth of LBW babies. These factors should be addressed with appropriate measures so as to decrease the prevalence of low birth weight among term babies in Nepal.     

Expression and characterization of N-terminal domain of Epstein-Barr virus latent membrane protein 2A in Escherichia coli

Latency of Epstein-Barr virus (EBV) is maintained by the transmembrane protein latent membrane protein (LMP) 2A, which mimics the B-cell receptor (BCR) and perturbs BCR signaling. LMP2A contains a cytoplasmic N-terminal domain composed of 119 amino acids, which provides signals that are responsible for the association with various signal molecules, resulting in negative regulation of B-cell signaling and the EBV lytic cycle. In the present study, to obtain N-terminal domain of LMP2A (LMP2A NTD, 13 kDa) in Escherichia coli for structural analysis, a strategy for obtaining the unfused form of LMP2A NTD without any fusion partners was proposed. Recombinant LMP2A NTD has previously been expressed using the GST fusion system in E. coli [Virology 268 (2000) 178, J. Virol. 71 (1997) 4752, Mol. Cell. Biol. 20 (2000) 8526]. However, we were unable to obtain untagged LMP2A NTD from this construct because of rapid proteolysis by thrombin. To overcome the proteolysis by thrombin, C-terminal His-tagged LMP2A NTD and intein-fused LMP2A NTD were prepared. As a result, LMP2A NTD without a fusion partner could be successfully obtained using non-enzymatic cleavage. The secondary structure of the recombinant LMP2A NTD was analyzed using circular dichroism. In aqueous solution, LMP2A NTD adopts an unordered structure, which was not affected by varying pH and salt concentration. In addition, any secondary structural components of LMP2A NTD were not induced in the membrane-mimicking environments, suggesting that LMP2A NTD may intrinsically have a random coil-like structure. The biological activity of recombinant LMP2A NTD was monitored by chemical shift perturbation in HSQC spectra of LMP2A NTD with or without WW domains, which result supports that the structural change induced by WW domains is restricted within narrow region.